I'd heard that the current Marvel contracts contained clauses to prevent anyone from retaining the rights to characters if they attempt to produce poor-quality, low-budget garbage just for the sake of retaining the rights. I think only theatrically released films count towards renewing the contracts, also. They can't just keep churning out direct-to-video stuff.

As for the 94 FF film, I don't think Fox was necessarily involved in that. Could be wrong, though. It was, however, definitely produced to retain the rights for the company making it at the time.